No, you don't, because they already have integrated Graphic cards. If you don't plan on gaming, the video cards are good enough for daily use. But if you want to game, get a discrete video card more suited to that task.
Yes and no. Depending on which version you buy of either cpu, they may or may not have onboard graphics. Even if the model you choose does have internal graphics, they are very limited. They will be fine for surfing, word processing, etc., but virtually useless for gaming.
No, you don't, because they already have integrated Graphic cards. If you don't plan on gaming, the video cards are good enough for daily use. But if you want to game, get a discrete video card more suited to that task.
We need to know your needs. That is what will you use your PC for, gaming, websurfing, Video Editing, etc..
This information is important to know for us.
But I will give you a rough idea.
--> If you are Gaming, then the Integrated GPU is not enough.
--> If you are Video Editing then you might or might not need a GPU depending on what softwares you use.
--> If you are using the PC for web surfing or Word Processing or watching Blu-Ray movies, then you would not need an external GPU as the Integreated GPU is more than enough for those purposes
I hope this helps. But please give us more details like what are you going to do with this build. We need to know that.